Oxygen therapy is the administration of oxygen as a therapeutic modality. It is widely used for a variety of purposes in both chronic and acute patient care as it is essential for cell metabolism, and in turn, tissue oxygenation is essential for all physiological functions. Oxygen therapy should be used to benefit the patient by increasing the supply of oxygen to the lungs and thereby increasing the availability of oxygen to the body tissues, especially when the patient is suffering from hypoxia and/or hypoxemia. Oxygen therapy may be used both in applications in hospital or in home care. The main home care application of oxygen therapy is for patients with severe chronic obstructive pulmonary disease (COPD).
Oxygen may be administered in a number of ways. A preferable way of oxygen administration is by using a so called on demand generation of oxygen. Referring to this, commercial solutions, so-called oxygen concentrators or separators, respectively, are widely known. These oxygen concentrators mostly separate oxygen from an oxygen comprising gas, so that the oxygen is provided on demand, i.e. directly before use. Most known oxygen concentrators require a compressor to compress the oxygen comprising gas. Furthermore, oxygen, preferably pure oxygen, has to be generated. Most known oxygen concentrators thus comprise an organic membrane to separate oxygen from the oxygen comprising gas.
The major drawbacks of the known oxygen concentrators are high costs and a limited convenience with respect to noise. Furthermore, undesired constituents of the oxygen comprising gas, mostly nitrogen, are adsorbed on the membrane thereby causing the requirement of a so-called swing process by which the adsorbed gas is desorbed from the membrane. During that desorption step, a separation of oxygen is not possible, because of which two membranes are desired which further increases the costs. Apart from that, the compressors are mostly noisy leading to a decreased convenience especially when the oxygen concentrator is used overnight. Furthermore, the generated oxygen is non-sterile, because of which a further measure of disinfection is often desired or necessary.
Known from U.S. Pat. No. 6,544,404 B1 is an oxygen separation process for the separation of oxygen from an oxygen containing fluid. This process uses mixed ionic and electronic membranes having a chemically active porous coating selected from the group consisting of metals, metal oxides and combinations thereof. This prior art wants to address the object of providing superior flux without sacrificing mechanical and physical compatibility of the composite membrane. However, these kinds of membranes require a certain amount of partial pressure difference between the primary side and the secondary side of the membrane, which in some cases is preferred to be avoided.
Additionally, there are known methods for separating oxygen which use pure voltage driven membranes, or pure ionic conductive membranes, respectively, having electrodes as outer conductive layers in order to generate an oxygen flux through the membrane. One major drawback of these membranes, or the use of the latter, respectively, may be seen in the fact that these membranes may require elevated temperatures in order to work properly. Under these conditions, however, there is the risk of components of the electrodes to be released from the electrodes which consequently are present in the stream of generated oxygen. In some applications, for example in the field of therapeutic applications, however, the presence of these compounds has to be avoided or at least significantly reduced. Additionally, arrangements being used for performing this method in some cases require an intense servicing work. Apart from that, electrodes being present on the surface of the membrane have to be permeable for gas or at least for oxygen, which might require a rather complex manufacturing process.